Method and device for digital modulation with low transition density
AssigneeCommissariat a l'energies atomique et aux energies alternatives
InventorsFlorian Pebay-Peyroula, Jean-Baptiste Dore
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Abstract
The present invention relates to a digital modulation method and a corresponding modulator. The modulator comprises a transcoder (110) followed by a FIFO register (120) and a 2-PSK modulator (130). The transcoder codes a binary word of fixed size into a code word of variable size using a transcoding table. The transcoding table codes at least one first binary word, leading to a first number of phase transitions at the output of the modulator, into a second word of size greater than that of the first word, leading to, at the output of the modulator, a second number of phase transitions less than the first number of phase transitions.
Claims12
A digital modulation method for transforming a sequence of input words (wk), each constituted of m information symbols, into a sequence of M-PSK modulation symbols where M=2m, wherein said method comprises:
- a step of transcoding wherein each input word (wk) is coded into a code word (w′k) of variable length by means of a transcoding table, the transcoding table coding at least one first input word, leading to a first number of phase transitions in said sequence of modulation symbols, into a second word of size greater than m, leading to a second number of phase transitions less than said first number in said sequence;
- a step of concatenation of the code words (w′k) obtained at the preceding step to supply a sequence of output words (w″k), each output word being constituted of m information symbols;
- and
- a M-PSK modulation supplying for each output word of the sequence a corresponding M-PSK symbol.
A digital modulator for transforming a sequence of input words (wk), each constituted of m information symbols, into a sequence of M-PSK modulation symbols where M=2m, wherein said digital modulator comprises:
- a transcoder wherein each input word is coded into a code word of variable length using a transcoding table stored within the transcoder, the transcoding table coding at least one first word, leading to a first number of phase transitions in said sequence of modulation symbols, into a second word of size greater than m leading to a second number of phase transitions less than said first number in said sequence;
- a FIFO register adapted to concatenate code words obtained at the preceding step to supply a sequence of output words (w″k), each output word being constituted of m information symbols;
- and
- a M-PSK modulator supplying for each output word a corresponding M-PSK symbol.
Dependencies are inferred from the claim text.